Reactive Molecular Dynamics Study on Material Removal Mechanism of Chemical Mechanical Planarization with Silica Substrate and Abrasive Grain

Chemical mechanical planarization (CMP) is an essential technique for processing semiconductor wafers that require ultra-smooth surfaces. The material removal mechanisms in this process, which are complicated because of the intertwined mechanical and chemical effects of abrasive grains and chemical solution, remain to be revealed. In this study, we conducted molecular dynamics simulation using ReaxFF focusing on the polishing of a silica substrate by a silica abrasive grain in an aqueous environment. To mimic different material removal modes, namely scratch and adhesion between the substrate and abrasive, we performed two methods of controlling the abrasive motion; i.e., displacement control and force control. Material removal was observed in both the two control methods. The formation of atomic bonds between the substrate and abrasive grain was not directly related to the amount of material removal. Our results also indicate that heat due to plastic deformation of the abrasive grain may affect material removal.